A quantitative analysis of the effects of nitrogen on the growth, development and yield of oilseed rape

Abstract

Two experiments carried out in 1968 and 1969 are described which examined, through growth and yield analysis, the effect of nitrogen on the growth of oilseed rape. The results of the second experiment, when 0, 105-5 and 211-0 kg N/ha were compared, are presented and discussed. The application of nitrogen increased the yields of seed and oil, principally through increased production of seeds by a larger number of pods. However, the application of nitrogen had little effect on average pod weight or average seed weight. Crop growth rates were increased by the application of nitrogen and reached their highest levels during the period of pod development when the leaf areas had declined to very low levels. The order of effects of nitrogen (N 2 > Nl > NO) was similar for LAI, number of pods per plant and number of seeds per pod and it is likely that the effect of nitrogen was achieved indirectly through an increase in the supply of assimilates to the flowers and young pods. This suggests that the maintenance of a large and photosynthetically efficient leaf area during the period of flowering is necessary for high yields in this crop.The results also suggest that once pods are macroscopic they produce much of the assimilates needed for their own growth.The implications of these findings with regard to both practice and further research are discussed.There is renewed interest in the oilseed rape affected by the treatments and to assess the relative crop in Great Britain resulting from its use as a importance of any effects on the yield of the econo-'break' crop in intensive cereal systems. Bunting mic product. (1969) has reviewed the published information on As pointed out in the preliminary report of this oilseed rape but much of it is derived from surveys, work (Allen, Morgan & Ridgman, 1971), there have old experiments or experiments carried out in been very few intensive field studies of the effect of Scandinavia and Canada, where the crop is grown genotype and agronomic treatment on the growth extensively under climatic conditions different from and yield of seed crops, other than cereals, those in Great Britain. Thus, there is very limited Information from this type of analysis is of imexperimental evidence on the performance of the portance to the agronomist in manipulating crop in this country. In view of this dearth of in-the crop's environment to best advantage and formation a series of experiments was begun in to the plant breeder in providing physiological Cambridge in 1968 to examine the effect of nitrogen, selection criteria, variety and row width on the growth and development of the crop. The preliminary experiment in 1968 and a more detailed study in 1969 are consi-T H E EXPERIMENTS dered here. The experimental approach followedThe experiments were carried out in 1968 and was both analytical and physiological, so that in 1969 on soils of the Milton series derived from old addition to studying effects on the ultimate yield r i v e r gravel and well supplied with phosphate and of oil, an attempt was made to...

Development of a Statistical Crop Model to Explain the Relationship between Seed Yield and Phenotypic Diversity within the Brassica napus Genepool

“…Several studies have sought to understand the contribution of individual traits to oilseed rape yield [4,6,[32][33][34][35] or to model yield such that it can be predicted over future growing seasons [5,7,8,36]. However, there is some disagreement between the studies as to what are the most important traits that influence yield, be it the number of pods per plant [34], the time to maturity [6] or the duration of flowering [32].…”

“…Once a seed contains the minimum amount of resources necessary to ensure germination viability, then there is no advantage for a plant in investing more resources beyond this in an individual seed, and a better survival strategy is to make more seeds in different pods, a view also reported in a study on Arabidopsis resource allocation [19]. Similarly, the addition of N was found to increase oilseed rape yields through the production of more pods as opposed to affecting individual seed or pod weight [33], something also observed in Year 1 of the current trial where plants were grown on high and low N.…”

Factors affecting nitrogen concentration in spring oilseed rape (Brassica napus L.)

“…With the delay of nitrogen application time till 4-5 leaf stage or even the start of flowering nitrogen concentration tended to increase. It is known that with nitrogen application at sowing plant weight and the number of lateral low-productivity branches is increasing (Allen and Morgan 1972). Therefore it is possible that when nitrogen fertilizer was applied at sowing most of it was used by plants to produce more vegetative mass and the concentration decreased as compare to nitrogen application at 4-5 leaf stage or at the start of flowering.…”

Hormones and Pod Development in Oilseed Rape (Brassica napus)

“…Therefore, with the goal of improving understanding on relationships between PGRs and pod development, we measured endogenous levels of IAA, ABA, Z, [9R]Z, iP, and [9R]iP in pods of field grown oilseed rape plants from 1 to 47 d postanthesis.…”